What do the following two equations represent? $5x+4y = 4$ $-12x+15y = 1$
Explanation: Putting the first equation in $y = mx + b$ form gives: $5x+4y = 4$ $4y = -5x+4$ $y = -\dfrac{5}{4}x + 1$ Putting the second equation in $y = mx + b$ form gives: $-12x+15y = 1$ $15y = 12x+1$ $y = \dfrac{4}{5}x + \dfrac{1}{15}$ The slopes are negative inverses of each other, so the lines are perpendicular.